Florida Wastewater Practice Test

Which condition reflects effective normal operation of an anaerobic digester?

1. Excessive gas production

2. Influent with high solids content

3. Monitoring without adjustment

4. Settling and decanting as required

The correct answer is: Settling and decanting as required

Effective normal operation of an anaerobic digester is characterized by the ability to settle and decant as required. This process indicates that the digestion system is functioning properly, maintaining an optimal environment for microbial activity, and allowing for the efficient breakdown of organic solids. When settling occurs, it means that the heavier solids are accurately being separated from the liquid fraction. This is crucial for the digestion process, as it allows the digester to maintain a healthy balance of solids and ensure that the microorganisms can effectively consume the organic material present. The decanting aspect signifies that the treated effluent can be removed from the system without disturbing the settled solids, allowing for a continuous treatment process. While excessive gas production may suggest strong microbial activity, it can also indicate issues such as overloading or imbalanced system operations. Similarly, influent with high solids content can pose a challenge to the digester's performance if not managed correctly. Monitoring without adjustment implies a lack of active management and can lead to problems if the system veers off optimal conditions. Thus, the ability to settle and decant properly is a direct indicator of the digester's operational effectiveness and stability.